Many different welding techniques and processes have been developed for joining metal materials together. When metal materials are joined by welding, the physical integrity of the structural member formed is typically limited by the weld zone properties. The weld zone consists of weld filler material, a heat affected zone (HAZ), and the material joined. Significant distortion may occur in thick section members joined together by a welding process. Asymmetry of the weld, of the weld process with time, asymmetry of the weld filler build, and unbalanced residual stresses are primary causes of such distortion. In welding thick parts or materials having a high thermal conductivity, the substantial heat sinking property of such parts or material poses problems in obtaining satisfactory welds that specifically insure sidewall penetration and pass-to-pass penetration. To overcome these problems, known welding techniques typically utilize plural low volume weld passes and substantial preheating of parts in an effort to limit distortion, and insure weld penetration. Such techniques tend to limit the geometry of the parts joined, limit weld production rates, limit the physical integrity of the weld, and tend to increase the cost of production. The physical integrity of the weld filler, and the region (zone) of softened parent material resulting from the welding process, are primary limitations of the known techniques.
The problems noted above in welding metal members together are of particular concern when the associated materials are high performance materials and the application is high consequence. Examples of high performance material are precipitation hardenable alloys. Such alloys include but are not limited to nickel, aluminum, and copper dominated metals, and so forth. Copper-beryllium-nickel alloy plate material is one particular example of such precipitation hardenable alloy materials, and is of particular interest to the present invention, but the present invention is applicable for use with many other such materials. A number of references attempting to solve problems in the prior art associated with such materials, and the joining of members constructed of such material, are discussed below.
Swift, U.S. Pat. No. 1,986,303, teaches a method for welding copper, or copper alloys. It is indicated that carbon arc welding is preferred for welding copper alloys of copper. The method uses a higher voltage in the welding process to provide a longer arc, for producing stronger welds.
Corson et al., U.S. Pat. No. 1,990,168, teaches the heat treatment of copper alloys. More particularly, the heat treatment of copper beryllium alloys is taught.
Munson, U.S. Pat. No. 2,027,750, teaches a copper base alloy for providing improved hardness, strength, ductility, and a wide heat treating temperature range. Heat treating ranges are given for the various compositions shown.
Harrington, U.S. Pat. No. 2,275,188, teaches a process for improving the properties of precipitation hardenable copper base alloys. The alloys are subjected to "double aging".
Cooper, U.S. Pat. No. 2,325,041, teaches a method for joining beryllium into copper. The precipitation hardening of alloys of beryllium copper is discussed.
Turner, U.S. Pat. No. 3,031,568, teaches a process for arc welding copper material. The process involves welding copper in the presence of an inert gas, along with a welding filler rod mainly comprising copper, and also including boron.
Gilliland, U.S. Pat. No. 4,119,830, teaches a control system for providing remote welding of materials. The system includes remotely controlled motors for automatically feeding welding wire to the weld site, and control circuitry for controlling the operation of the welding head.
Wikle, U.S. Pat. No. 4,179,314, teaches a process for double age hardening of alloys of beryllium-copper.
Mesick et al., U.S. Pat. No. 4,355,224, shows the use of a coated electrode for use in arc welding.
Godai et al., U.S. Pat. No. 4,336,441, teaches a welding process for providing a particular composition for welding wire used in a TIG (tungsten inert gas) welding process, whereby the arc and welding head are controlled for oscillating or weaving the resultant weld bead as it is being applied to the pieces being joined. Note in columns 15 and 16 of this patent, it is indicated that heat treatment of the weld bead is provided by the arc heat from the non-consumable electrode.
Stol, U.S. Pat. No. 4,447,703, teaches a welding method for preheating a consumable wire electrode immediately prior to melting in an electric arc during the welding process. Both tungsten inert gas and metal inert gas processing is taught.
Pedersen et al., U.S. Pat. No. 4,460,659, teaches a copper alloy welding filler composition for use in arc welding copper. The composition includes boron. and zirconium with copper.
Bosna, U.S. Pat. No. 4,539,465, teaches a system for both storing and feeding welding wire. The system is included in a robotic welding system.
Inagaki, U.S. Pat. No. 4,594,116, teaches a method for processing copper-beryllium alloys. The process includes heat treating the alloy at a temperature of 750.degree. to 950.degree. for a period of time within a range of one to four hours.
Church et al., U.S. Pat. No. 4,724,013, teaches a method for heat treating copper beryllium alloys.
Penney et al., U.S. Pat. No. 4,724,302, teaches a robotic system for controlling the feeding process in welding processes, for example.
Bienek et al., U.S. Pat. No. 4,738,388, teaches a process for sealing a container storing radioactive material. A welding seam 17 is used in order to seal a cover or lid to the container.